1. Field of the Invention
The present invention relates to an image heating apparatus to be used in an image forming apparatus, such as a copier and a laser beam printer (LBP), which adopts an image forming process of an electrophotographic system or an electrostatic recording system. As such an image heating apparatus, there is known a fixing apparatus for heating and fixing an unfixed toner image formed on a recording material (transfer material, printing paper, photosensitive paper, electrostatic recording paper, etc.) as a fixed image. Further, there is also known a glossiness enhancing apparatus for enhancing the glossiness of an image by heating the image fixed to a recording material.
2. Description of the Related Art
Hitherto, as a fixing apparatus provided in an image forming apparatus such as a copier, a printer, and a facsimile of an electrophotographic system, a contact-heating type, heat-roller system having satisfactory thermal efficiency and a film heating system having quick start property (on-demand property) have been used. The fixing apparatus of a film heating system can realize a small heat capacity and suppress power consumption during a standby state through the use of a heat-resistant film or a metal sleeve (hereinafter referred to as “fixing sleeve”) serving as a hollow rotatable heating rotary member which is heated by a heating source, and hence this fixing apparatus provides excellent energy savings. Specifically, Japanese Patent Application Laid-Open No. H04-44075 discloses a fixing apparatus of a film heating system.
In the fixing apparatus as described above, a recording material bearing an image is conveyed to a nip portion formed between a heating rotary member and a pressure member, and is nipped therebetween to heat the image. The fixing apparatus includes a holding member provided at an end portion in a rotation axis direction of a fixing sleeve serving as the heating rotary member, and the holding member includes a regulation surface for holding an inner surface of the fixing sleeve at a position on an upstream side of the nip portion, and a regulation surface for regulating the movement in the rotation axis direction of the fixing sleeve. Specifically, a fixing flange includes a regulation surface serving as a shift regulation member, as well as a regulation surface serving as a holding member to be brought into internal contact with a fixing sleeve end portion to stabilize the shape of the fixing sleeve during rotation.
However, in the above-mentioned related art, when the movement force (shift force) in the rotation axis direction (thrust direction) of the fixing sleeve is too strong, there is a risk that the end surface of the fixing sleeve and the shift regulation member strongly rub against each other to shave and damage the shift regulation member and the metal sleeve. Alternatively, there is a risk that the end portion of the fixing sleeve buckles and is damaged.